I. Field of the Invention
The present invention relates to a variable coupled inductor and, in particular, to a variable coupled inductor can improve efficiency in both light-load and heavy-load situations.
II. Description of the Prior Art
A coupled inductor has been developed for a period of time; however, it is not often used in the circuit board. As a more powerful microprocessor needs a high current in a small circuit board, a variable coupled inductor has been gradually used in the circuit board. A variable coupled inductor can be used to reduce the total space of the circuit board consumed by traditional coupled inductors. Currently, a coupled inductor can reduce the ripple current apparently, wherein a smaller capacitor can be used to save the space of the circuit board. As the DC resistance (direct current resistance, DCR) of the coupled inductor is low, efficiency is better in a heavy-load situation. However, as the flux generated by each of the dual conducting wires will be cancelled each other when the dual conducting wires are coupled, the inductance becomes low and the efficiency becomes worse in a light-load situation.